The driving of two or more shafts so that they rotate in a precisely matched manner requires the use of a gearing system having precisely meshed gears. Such a system is required in many different instances. For example, when driving two rollers of a rotary chopping device having blades mounted on rollers, the blades being required to meet and overlap to provide a cutting action, it is desirable that the gears connecting the two drive shafts shall be driven through gears in which there is no backlash. While this condition may be possible to achieve with new gearing, as the system wears, it is desirable to provide some means to take up any backlash.
In the past, systems have been available in which two gear halves having straight teeth were provided for taking up the backlash, one gear half being capable of being adjustably rotated relative to the other. However, such systems are not entirely satisfactory, and result in the development of considerable wear on one or other gear half. They also result in uneven wear occurring on the meshing gear.